Scanning Electron Microscope and Epiretinal Membranes in Vitreoretinal Surgery

Abstract

Purpose: To study the utility of Scanning Electron Microscope in vitreoretinal samples.

Methods: 10 specimen of 10 patients affected by various interface pathologies were taken during 3 port pars plana vitreoretinal surgery. The specimen were fixed in buffered 4% paraformaldehyde and 0.1% glutaraldehyde and postfixed in a solution of 1 % osmium tetroxide and 1,25% potassium ferrocyanide for 1 h, then transversally cut with a razor blade in order to better expose the inner organization, dehydrated in ethanol, dried in hexamethyldisilazane and observed in a Philips SEM-FEG XL 30.

Results: The specimens appeared as laminar connective structures partially or completely adherent to the inner limiting membrane (ILM). Our observations evidenced three types of structures from the ILM to the vitreous: a) thin sheets of woven fibres; the sheets created distinct layers; b) folded layers of inhomogeneous thickness of fibrous material more consistent in some cases recognizable as collagen fibrils with typical 67 nm period. Collagen fibrils are isolated or intermingled each other; c) lacunar structures with inflammatory and/or necrotic material. The three types of tissue seem to evolve as a thickening from the ILM to the vitreous in order a) to c). The interface between the ILM and the epiretinal tissue shows particular little bridges of connection. Cells are rarely found, especially in tissue near the ILM.

Conclusions: Epiretinal membranes of different pathologies show different layers of tissues. Fibroblasts cells produce material and then migrate gradually to the interior part of the eye. Scanning Electron Microscope could be very usefull in understanding the pathological tissues ultrastructure and its mechanism of formation, helping us to understand the correct modality of their pharmacological or surgical excision.

Keywords: 597 microscopy: electron microscopy • 762 vitreoretinal surgery • 419 anatomy